Unlicensed mobile access networks (UMANs) have been developed that provide numerous advantages relative to conventional cellular radio access networks. For example, a UMAN may be faster in some situations than conventional cellular radio access networks and/or may be less expensive to utilize than some conventional cellular radio access networks. Thus, it is advantageous in at least some situations to access a core network via a UMAN as opposed to a more conventional cellular radio access network.
A UMAN generally includes an access point, such as a transceiver, for communicating with a mobile station in an unlicensed spectrum, such as by means of Bluetooth™ brand wireless access technology developed by the Bluetooth Special Interest Group, wireless local area network (WLAN) techniques such as IEEE 802.11, WiMAX techniques such as IEEE 802.16 or the like. The access point of the UMAN is connected to a unlicensed network controller via a broadband IP access network. The unlicensed network controller, in turn, supports communication with the core network such that the mobile station can communicate with the core network ostensibly in the same manner from the user's perspective as if the communications were supported by a conventional cellular radio access network.
In use, a mobile station involved in a communication session supported by a cellular radio access network may transition to a location supported by a UMAN. In this scenario, the communication session is desirably handed off from the cellular radio access network to the UMAN in a seamless manner such that subsequent communications are supported by the UMAN, at least up until the mobile station moves to a location outside of the coverage area of the UMAN.
In order to provide access to GSM (Global System for Mobile communications) and/or GPRS (General Packet Radio Services) services via a UMAN, a technical specification for the unlicensed mobile access (UMA) technology has been developed. See the UMA Architecture (Stage 2) R 1.0.1 technical specification dated Oct. 8, 2004 (hereinafter the “UMA architecture specification”). The UMA architecture specification defines the manner in which a communication session is handed off from a GSM/GPRS radio access network to a UMAN. See Section 9.10 of the UMA architecture specification. Assuming that the mobile station is configured so as to prefer communications via a UMAN as opposed to a GSM/GPRS radio access network and further assuming that the mobile station has detected and successfully registered with a UMAN, the mobile station, the base station controller of the GSM/GPRS radio access network, the unlicensed network controller and the core network conduct a predefined signaling sequence in order to successfully handoff the communication session from the cellular radio access network to the UMAN.
In this regard, the UMAN is assigned an absolute radio frequency channel number (ARFCN) and a base station identity code (BSIC) for identification purposes within the GSM/GPRS network, and the base station controller is provided not only with the ARFCN and BSIC of the UMAN, but also an association between the ARFCN and BSIC of the UMAN and the cell global identification (CGI) of the UMAN. Thereafter, upon the detection of a UMAN, the mobile station initially provides a measurement report to the base station controller that reports the highest signal level for the UMAN which is identified by its ARFCN and the BSIC. The base station controller identifies the CGI of the UMAN upon recognizing that the highest signal level is associated with another network, in this instance, the UMAN. The base station controller then initiates the signaling sequence required to hand over communications from the GSM/GPRS radio access network to the UMAN. Once the handover is complete, the mobile station can communicate with the core network via the UMAN, oftentimes in a faster and less expensive fashion than similar communications via a GSM/GPRS radio access network.
Unfortunately, the UMA architecture specification only provides for handoff from a GSM/GPRS radio access network to a UMAN and does not support the handoff of a communication session from other types of cellular radio access networks to a UMAN. In this regard, the ARFCN and BSIC that are utilized to identify the UMAN are specific to GSM/GPRS technology and are not utilized in conjunction with other types of cellular networks, such as code division multiple access (CDMA) networks.
For UMANs to further gain in popularity and acceptance, it would be desirable to facilitate the handover of communication sessions from various types of cellular radio access networks, including CDMA radio access networks, such that a mobile station may travel more freely between radio access networks without concern that the communication session will be interrupted and while permitting the mobile station to take advantage of communication via UMANs that are available even if the mobile station was previously supported by a cellular radio access network other than a GSM/GPRS radio access network, such as a CDMA radio access network.